Antimicrobial activity of cuprous oxide-coated and cupric oxide-coated surfaces.

Background: Disease can be spread through contact with contaminated surfaces (fomites). For example, fomites have been implicated in the spread of meticillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. Antimicrobial surface treatments are a potential method of reducing disease transmission from fomites, and broad-spectrum activity is desirable.

Aim: To test cuprous oxide (CuO) and cupric oxide (CuO) coatings for antimicrobial activity against 12 micro-organisms including bacteria and fungi.

Methods: We fabricated two surface coatings. The CuO coating was fabricated in a simple two-step process using polyurethane to bind the active copper oxide particles; CuO was prepared by heat treatment of CuO particles in air to produce cupric oxide (CuO) and to cause early-stage sintering to form a continuous coating. The antimicrobial activity was examined with 10 μL of microbial suspension droplets followed by counting cells as colony-forming units (cfu).

Findings: The coatings rapidly killed nine different micro-organisms, including Gram-negative and Gram-positive bacteria, mycobacteria and fungi. For example, the CuO/PU coating killed 99.9997% of P. aeruginosa and 99.9993% of S. aureus after 1 h. Efficacy was not reduced after weekly cleanings. The antimicrobial activity of the CuO coating was unchanged after abrasion treatment, and the coatings were not cytotoxic to human cells.

Conclusion: The combination of broad-spectrum antimicrobial activity, abrasion resistance, and low toxicity of the CuO coating suggests potential use in healthcare settings.